The current (1.3.11) documentation to expire vacation messages reads as follows:

Cronjob — Vacation messages expiration
When vacation messages are enabled (see the parameter “SOGoVacationEnabled”), users can
set an expiration date to messages auto-reply. For this feature to work, you must create a
cronjob under the “sogo” user. This cronjob should be run daily and defined like so :
0 /path/to/sogo-tool expire-autoreply

This will not work, since we need to specify the sieve admin user and password on the command line, just behind the expire-autoreplay

The last line should be changed to something like:

0 /path/to/sogo-tool expire-autoreply <sieveadminuser:sieveadminpassword>

and tell in the documentation about the need of a sieve admin user to expire the vacation messages